One of the most common types of heart surgery is coronary artery bypass grafting, or CABG. In CABG, a blockage in one or more coronary arteries is bypassed by connecting a graft vessel to the coronary artery downstream of the blockage. The technique of connecting the graft vessel to the coronary artery is known as anastomosis. The graft vessel may be a mammary artery dissected from the chest wall, where the upstream end of the artery is left intact and the downstream end is attached to the coronary artery. Alternatively, the graft vessel may be a section of artery or vein from elsewhere in the patient's body, or an artificial vascular graft, where the upstream end of the graft is attached to an artery such as the aorta, and the downstream end is connected to the coronary artery downstream of the blockage.
Where more than one bypass is required, the graft vessel most commonly used is the great saphenous vein. The great saphenous vein, referred to hereinafter as the saphenous vein, is the longest vein in the body. It begins on the medial side of the foot, rises to extend up along the inner side of the leg, and penetrates deep into the thigh just below the inguinal ligament in the lower abdomen, where it joins the femoral vein. Near its distant end, the saphenous vein receives vessels that drain the upper thigh, groin, and lower abdominal wall. Due to its length, once harvested, doctors can cut the saphenous vein into multiple grafts, and then use each graft to “jump” a blockage in a different coronary artery by attaching a proximal end of the graft to an artery that supplies oxygenated blood and the distal end of the graft to the coronary artery downstream of the blockage.
In recent years, there have been great strides in the harvesting of veins using less-invasive techniques. The technique has evolved from an open “fillet” procedure, where the surgeon cuts down through the tissue overlying the saphenous vein to harvest the vein, to less-invasive procedures, where the surgeon harvest the vein by using an endoscopic device passed through one or more small incisions. Examples of these techniques are described in U.S. Pat. Nos. 5,928,138 and 6,193,653, which are hereby incorporated by reference. The small incisions of the less-invasive techniques heal more readily, with fewer complications and far less pain, than the open procedures.
To perform the less-invasive techniques, however, the surgeon, physician's assistant or registered nurse first assistant needs to master an endoscopic procedure, which requires training before the surgeon becomes proficient. The surgeon gains experience by performing the endoscopic procedure on pigs, cadavers or on models. In any case, the procedures performed on an animal or on a cadaver or prior art models do not accurately reflect the clinical conditions. Pig anatomy is not the same as the human anatomy, and the cadaver tissue does not simulate live tissue. Further, while commercially available prior art models from, for example, Limbs 'n Things (www.limbsandthings.com) and the Chamberlain Group (www.thecgroup.com), provide models having veins that contain simulated blood, the models do not provide realistic training for dissection of the vein from the surrounding tissue using endoscopic tools. These products are often designed such that the housing, which is often formed to take the appearance of a human leg, and the tissue that surrounds the vein is reusable. In these cases, the vein casting is designed to be replaceable, which means that the vein casting must be relatively easily removable from the material that surrounds the vein casting. As a result, the veins of these models are disposed in relatively loose material, such as polyester batting. Thus, the dissection or separation of the saphenous vein from the surrounding tissue is much easier with the models as compared with the real procedure.